How Sheltering Works

A shelter works by interrupting exposure pathways. No single component addresses every radiological hazard.

Airborne pathway

Radioactive aerosols and other airborne material can enter a building through ventilation, openings and leakage. Airflow control and appropriate filtration are the principal engineering controls for this pathway.

External radiation

Gamma radiation outside the protected room is reduced by mass, geometry, distance and room position. Positive pressure does not provide gamma shielding.

Internal contamination

Contamination control also depends on behaviour: controlled entry, separation of clean and potentially contaminated items, monitoring where appropriate, and procedures for occupants.

Duration

A technically protected room must remain habitable. Power, ventilation, carbon-dioxide management, water, sanitation, communications and maintenance therefore become increasingly important as shelter duration increases.